Keeping up with its promise to help the US Congress to probe misinformation spread on its platform via Russian ads during the US presidential poll, Facebook has blocked a researcher from viewing the ads on its social media site.

A report in The Washington Post late on Thursday said that the researcher had looked at the information to study the reach of ads associated with an alleged Kremlin-backed campaign and was still combing through Facebook posts when the social networking giant deleted them from the public record.

“Analyst Jonathan Albright had downloaded posts from six of the Facebook pages before learning information from all 470 accounts was no longer publicly available,” the report said. According to Albright, Facebook said the information was not meant to be public and the company considered it a “bug” that he was able to find and download the data through the Facebook-owned social media analysis tool CrowdTangle.

Facebook confirmed it fixed the flaw in CrowdTangle that allowed Albright to see information from inactive Facebook pages, CNet reported. The flaw had exposed the content that was already deleted from Facebook pages. “Across all our platforms we have privacy commitments to make inactive content, that is no longer available, inaccessible,” a Facebook representative was quoted as saying.

On Wednesday, the US House Intelligence Committee leaders announced to make some of the 3,000 Russian ads public that appeared on Facebook during the 2016 US presidential election. The decision was taken after US Congress leaders met Facebook Chief Operating Officer Sheryl Sandberg late on Wednesday.